PROJECT SUMMARY Rapid weight gain and being overweight during early infancy have been associated with a greater risk for obesity during childhood and into adulthood. Thus, prevention efforts are much needed during infancy. Classic predictors of obesity during infancy such as breastfeeding and the timing of introduction of solids (i.e., after six months of age) have failed to demonstrate a protective effect. Hence, researchers and interventionists have moved their focus to maternal sensitivity to child cues. However, our understanding of the associations between maternal sensitivity to infant feeding cues and infant obesity risk is limited, as most prior studies focused on older children, with only a handful examining infancy. Studies with mothers of infants were mainly based on self-report surveys and/or used a cross-sectional design, which limit interpretation. No studies have observed maternal sensitivity to infant cues during naturalistic feeding interactions to investigate whether such maternal behavior is protective against rapid weight gain in infancy. In addition, most prior work has not considered the behavior of the infants themselves during the feeding interaction. Better understanding of the nature of the maternal-infant feeding interaction is critical for identifying maternal and infant behaviors that protect against obesity risk. Further, the correlates (e.g., maternal weight, child temperament) of maternal- infant feeding interactions are unknown. Understanding the correlates of observed maternal-infant feeding interaction would allow better identification of families and infants who are most at-risk. In the proposed study, we will leverage videotaped data from an ongoing longitudinal study to better understand maternal-infant behaviors during a naturalistic feeding interaction. Specifically, we will code maternal and infant behaviors at age 2 months using the well-validated and reliable Nursing Child Assessment Training (NCAST) Feeding Scale. The NCAST Feeding Scale has been used in various disciplines to capture maternal-infant feeding behaviors to predict child social-emotional and cognitive development, yet there is a lack of work investigating the associations between the NCAST Feeding Scale and obesity risk. The aims of the proposed study are: Aim 1. To describe maternal (i.e., sensitivity to infants' cues, responsiveness to infants' distress, social- emotional and cognitive growth fostering) and infant behaviors (i.e., clarity of feeding cues and responsiveness to caregiver) during a naturalistic feeding interaction at age 2 months. Aim 2. To examine whether maternal (weight, depressive symptoms, stress levels) and infant characteristics (sex and temperament) are associated with observed maternal and infant feeding behaviors at age 2 months. Aim 3. To examine whether observed maternal and infant behaviors at age 2 months, controlling for maternal and infant characteristics, predict weight status (weight-for-length z-score (WFLz)) at age 12 months.